Remove regex reference from rusti
Remove regex reference from rusti

The regex crate has been moved out of rust to crate.io. So rusti can't
use it as is any more. Removes the reference.

rust-lang/rust-playpen,lastorset/rust-playpen,epdtry/cse333-rust-slides,tilpner/rust-playpen,rust-lang/rust-playpen,Enamex/rust-playpen,lastorset/rust-playpen,rust-lang/rust-playpen,Enamex/rust-playpen,tilpner/rust-playpen,plietar/pony-playpen,epdtry/cse333-rust-slides,tilpner/rust-playpen,Enamex/rust-playpen,Enamex/rust-playpen,epdtry/cse333-rust-slides,lastorset/rust-playpen,chris-morgan/rust-playpen,chris-morgan/rust-playpen,lastorset/rust-playpen,chris-morgan/rust-playpen,plietar/pony-playpen,Limvot/kraken-playpen,chris-morgan/rust-playpen,Limvot/kraken-playpen,plietar/pony-playpen,Limvot/kraken-playpen,epdtry/cse333-rust-slides,plietar/pony-playpen,tilpner/rust-playpen,rust-lang/rust-playpen